The pair originally met on the set of That 70s Show, where they played on-screen lovers for eight years.

The pair didn't become romantically involved until Ashton split from his wife Demi Moore in 2011. An insider recently hinted that a proposal could be imminent, telling Us Weekly that Mila brings out the best in her boyfriend:

'They plan to get engaged soon. Being with Mila brought Ashton back to who he really is.'

The source added: ''He's not playing the field, he's focused on enjoying Mila and the happiness she brings. She doesn't get jealous like Demi used to. He calls her because he wants to and when they're apart they talk constantly.''

Old friends: The couple met on the set of That 70s show in the 1990s before getting together around a year and a half ago